1 00:00:02,040 --> 00:00:07,040 Speaker 1: Welcome to brain stuff from how Stuff Works. Hey, brain stuff, 2 00:00:07,080 --> 00:00:11,000 Speaker 1: Lauren vogelbamb here there's a myopia epidemic going on. In 3 00:00:11,119 --> 00:00:16,200 Speaker 1: n seventy two, about of Americans aged twelve to fifty 4 00:00:16,200 --> 00:00:18,880 Speaker 1: four were diagnosed with this condition, which is also called 5 00:00:18,960 --> 00:00:23,480 Speaker 1: near sightedness. But today some forty of young Americans are 6 00:00:23,520 --> 00:00:27,320 Speaker 1: receiving the same diagnosis. And that's nothing compared to Asian countries, 7 00:00:27,360 --> 00:00:31,400 Speaker 1: where of high school kids are now near sighted. In seal, 8 00:00:31,840 --> 00:00:34,720 Speaker 1: ninety six point five percent of nineteen year old males 9 00:00:34,760 --> 00:00:38,280 Speaker 1: are myopic, and researchers say that by the year twenty 10 00:00:38,360 --> 00:00:41,600 Speaker 1: fifty five billion people will be wearing glasses to combat 11 00:00:41,680 --> 00:00:44,360 Speaker 1: near sightedness. That's more than half the people in the world. 12 00:00:44,840 --> 00:00:47,240 Speaker 1: How did this happen so fast and so many people. 13 00:00:48,000 --> 00:00:50,519 Speaker 1: While intuitively you might think it has something to do 14 00:00:50,560 --> 00:00:52,800 Speaker 1: with all the time we spend staring at computer or 15 00:00:52,840 --> 00:00:56,040 Speaker 1: smartphone screens, it's not so cut and dried. The rise 16 00:00:56,080 --> 00:00:58,920 Speaker 1: and near sightedness started happening before the prevalence of those 17 00:00:58,960 --> 00:01:02,240 Speaker 1: screens and has been studied at least since the nineteen sixties. 18 00:01:02,920 --> 00:01:05,840 Speaker 1: The latest research reveals that the world's rising myopia rates 19 00:01:05,880 --> 00:01:09,720 Speaker 1: stem from spending too much time indoors in general, Several 20 00:01:09,720 --> 00:01:13,120 Speaker 1: studies show the less time children spend outdoors, the more 21 00:01:13,160 --> 00:01:16,240 Speaker 1: likely they are to develop myopia. This could explain the 22 00:01:16,400 --> 00:01:19,520 Speaker 1: much higher myopia rates in Asian countries, where a stronger 23 00:01:19,520 --> 00:01:22,840 Speaker 1: focus on education keeps kids indoors for more hours than 24 00:01:22,920 --> 00:01:26,000 Speaker 1: children living in most other parts of the world. We 25 00:01:26,040 --> 00:01:29,759 Speaker 1: spoke with Dr Adam Clarin, a Florida optometrist. He said 26 00:01:30,040 --> 00:01:32,800 Speaker 1: the progression of the number of myopic patients has risen 27 00:01:32,840 --> 00:01:36,319 Speaker 1: too fast to be explained by genetics alone. Unfortunately, the 28 00:01:36,400 --> 00:01:39,280 Speaker 1: data is not conclusive enough to determine what parts of 29 00:01:39,319 --> 00:01:42,840 Speaker 1: being outside is protective against myopia. Is that the sunlight, 30 00:01:42,959 --> 00:01:45,280 Speaker 1: is it looking at distant objects, or is it something 31 00:01:45,319 --> 00:01:49,040 Speaker 1: we're not even thinking about. Near sightedness is caused by 32 00:01:49,040 --> 00:01:52,880 Speaker 1: an elongated eyeball. Normally, the light that flows into your 33 00:01:52,880 --> 00:01:56,040 Speaker 1: eyes focused directly on the surface of the retina, but 34 00:01:56,080 --> 00:01:58,360 Speaker 1: if your eyeball is a bit too stretched out, the 35 00:01:58,440 --> 00:02:00,680 Speaker 1: lens will focus the lights slightly in front of the 36 00:02:00,720 --> 00:02:05,520 Speaker 1: retina instead, resulting in blurry vision. The hypothesis about myopia 37 00:02:05,560 --> 00:02:08,480 Speaker 1: that's gaining the most traction says that when the neurotransmitter 38 00:02:08,600 --> 00:02:11,600 Speaker 1: dopamine is released into the retina. It prevents your eyeball 39 00:02:11,639 --> 00:02:14,960 Speaker 1: from elongating and blurring your vision, and light is what 40 00:02:15,040 --> 00:02:19,080 Speaker 1: stimulates this release of dopamine. Normally, a pair of glasses 41 00:02:19,160 --> 00:02:22,560 Speaker 1: or contact lenses is all that's needed too sharpen your vision. However, 42 00:02:23,320 --> 00:02:25,840 Speaker 1: of those with the condition have a heightened form called 43 00:02:25,960 --> 00:02:28,959 Speaker 1: high myopia. People with high myopia are at a risk 44 00:02:29,000 --> 00:02:33,680 Speaker 1: for developing cataracts, glaucoma, torn or detached retinas, and even blindness. 45 00:02:34,520 --> 00:02:36,919 Speaker 1: Although no one knows how much time spent outdoors is 46 00:02:37,000 --> 00:02:40,440 Speaker 1: enough to forestall myopia, one researcher at the Australian National 47 00:02:40,520 --> 00:02:43,880 Speaker 1: University in Canberra estimated the amount at three or more 48 00:02:43,919 --> 00:02:47,600 Speaker 1: hours per day. It's also possible that strong indoor lights 49 00:02:47,600 --> 00:02:51,440 Speaker 1: could help, but Dr roheat Varma, director of the University 50 00:02:51,440 --> 00:02:54,600 Speaker 1: of Southern California I Institute, told us via email that 51 00:02:54,680 --> 00:02:57,120 Speaker 1: even if the myopia boom is not directly related to 52 00:02:57,200 --> 00:03:00,440 Speaker 1: children spending more time indoors looking at a screen quote, 53 00:03:00,760 --> 00:03:03,519 Speaker 1: these are two sides of the same coin. Spending more 54 00:03:03,560 --> 00:03:07,320 Speaker 1: time indoors equates to spending less time outdoors, especially during 55 00:03:07,320 --> 00:03:10,960 Speaker 1: the day. Researchers are still trying to determine the real 56 00:03:11,000 --> 00:03:15,000 Speaker 1: fix for the myopia epidemic. Dr Claarin said other studies 57 00:03:15,000 --> 00:03:17,600 Speaker 1: have shown that a low dose of atropine eye drops 58 00:03:17,639 --> 00:03:20,639 Speaker 1: can also slow the progression of myopia. These studies are 59 00:03:20,639 --> 00:03:23,840 Speaker 1: completely unrelated to the studies on being outdoors, so there's 60 00:03:23,840 --> 00:03:28,240 Speaker 1: obviously more than one mechanism at play. Hopefully, continuing research 61 00:03:28,280 --> 00:03:36,400 Speaker 1: will shed some light on this growing problem. Today's episode 62 00:03:36,400 --> 00:03:39,040 Speaker 1: was written by Bellinie redz Kien McManus and produced by 63 00:03:39,040 --> 00:03:41,560 Speaker 1: Tyler Clang. For more on this and lots of Far 64 00:03:41,680 --> 00:03:44,520 Speaker 1: Side of topics, visit our home planet, how Stuff works 65 00:03:44,680 --> 00:03:56,360 Speaker 1: dot com.